SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe2be30ef24e8720e5d1a5cfe8a9aeb3024e4019192588c4b971d8745e24310' 
  AND token = 'x2fDkUb8cEgKnSIal/y6dOBBpJuCKV+SYSco0ZKofuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}